In order to destroy the pride of Indra (the demigod who controls the rain), the Supreme Personality of Godhead, Krishna, recommended to his father, Nanda Maharaja, that they do not perform the sacrifice for Indra, but instead they should perfrom a sacrifice to please Govardhan Hill along with the cows and brahmanas. So the inhabitants of Vrndavana did all that Krishna suggested, using all the paraphenalia that had been intended for the sacrifice to Indra. They prepared many kinds of opulent foods, fed grass to the cows and all together circumambulated Govardhan Hill while the brahmanas chanted hymns and the ladies sang the glories of Krishna. When Indra understood that the inhabitants of Vrndavana had stopped the sacrifice meant for him, he became furious. Thinking that they had been overcome with arrogance, Indra ordered his strongest clouds to go to there to crush their pride and destroy their animals. These clouds of destruction sent down torrents of rain like thick columns, thunder and lightning, and excessive winds. The land of Vrndavana was submerged in a flood. Everyone turned to Krishna for shelter. Thinking of their protection, Lord Krishna picked up Govardhan Hill with one hand and held it above His head as easily as a child holds up a mushroom. Lord Krishna said, "O Mother, O Father, O residents of Vraja [Vrndavana], if you wish you may now come under this hill with your cows. You should have no fear that this mountain will fall from My hand. And don't be afraid of the wind and rain, for your deliverance from these afflictions has already been arranged. " Thus the residents of Vrndavana entered under the hill and their minds were pacified. -Summarized from Srimad Bhagavatam 10.25